1. Field of the Invention
This invention relates in general to magnetic recording systems and in particular to a recording system in which optimal recording of a wide spectrum of recorded frequencies is achieved.
2. Description Relative to the Prior Art
Conventional magnetic playback heads are sensitive to the time rate of change of recorded signal flux, i.e. EQU (d.phi./dt)
This would suggest, therefore, that higher recorded signal frequencies, which are characterized by maximized EQU (d.phi./dt)
are easier to recover than lower frequency recorded signals. Notwithstanding this suggestion though, higher frequency signals are subject to the counter-influencing playback phenomenon often referred to as "spacing loss". Spacing loss (S.L.) in decibels, as is known, varies in accordance with the following emperical expression EQU S.L.=55(d/.lambda.),
where d is head-to-medium spacing, and .lambda. is recorded wavelength; and, as will be appreciated, and in view thereof, those practicing the art of magnetic recording have long recognized the compelling need to provide (ordinarily) intimate contact between a playback head and a recording medium, the higher frequency recorded signals residing close to the surface of the recording medium where flux associated with such signals can easily close on itself.
Since spacing loss is inversely related to the wavelength of a recorded signal, its influence is barely felt in the playback of low frequency signals from a magnetic recording medium, such signals residing deep within the recording medium and relatively far from the medium's head contacting surface. Notwithstanding a low spacing loss manifestation for low frequency signals, however, such signals are intrinsically characterized by low rate of change of magnetic flux, and attendantly are not efficient in the production of good playback response.
Complex signals are typically composed of both high and low frequency signal commponents: Thus, at any given point along, say, the longitudinal axis of a magnetic tape, recorded flux patterns associated with both high and low frequency components may exist, the high frequency signal flux patterns residing at or near the surface of the tape, and the low frequency flux patterns residing beneath the high frequency flux patterns deeper within the cross-section of the tape. As a result, even with an excellent head-to-medium interface, playback of the lower frequency signal components may be less than would otherwise be desired.